1. Field of the Invention (Technical Field)
The present invention relates to radiometer horns and methods of manufacturing same.
2. Description of Related Art
It is necessary to package an array of corrugated (W-Band) Radiometer Horns in a tight grouping in order to achieve desired sensor performance for certain applications. A tight array leaves little additional volume around each horn, while the corrugated design of the horn creates a manufacturing challenge. Traditional manufacturing methods do not work due to the limited allowable volume for the horn (protruding fasteners interfere with the neighboring horn). The corrugated shape of these horns, as well as being of a small (W-Band) design, limits the potential to cast or electro-form this shape. The horns have to be built while ensuring complete electrical conductivity throughout the interior face of the horn, with minimal room for fasteners.
Similar (typically larger than W-Band) horns have been built with corrugated interior geometry, but the assembly methods employed do not yield a horn whose exterior volume is as small relative to the interior volume. The individual components that would be used to make other corrugated horns would not be press fit together. Instead, they would use multiple fasteners to ensure a tight press between each part. Often, these horns would then be dip braised to ensure a high degree of electrical conductivity.
Other horns have been manufactured with aluminum or other material, and then plated with gold or other highly conductive materials, to create the desired conductivity throughout the horns interior. This plating process would fail to evenly coat the small corrugations of our horns due to the flow of electrons in this geometry during the plating operation. For the same reasons, electro-forming methods could not be employed for a horn of this geometry and size.
The horns of the invention take advantage of a unique manufacturing method, known as Wire EDM (Electrical Discharge Machining), along with the corrugated shape, to create a press fit between the pieces of the horn. This press fit requires a highly precise manufacturing method to create three pieces that press together in such a way that electrical conductivity is maintained throughout the horn, yet the pieces do not bind or deform and fail to assemble correctly. The invention creates a highly effective W-band corrugated horn in a smaller volume, with fewer machining hours, for fewer resources than other methods. This allows for a better packaging environment to create a tight array of horns.